The sun and moon together represent duality: day and night, masculine and feminine, conscious and unconscious. It's a popular motif for balance, cycles of life, or honouring opposing forces that coexist. Some wear it for a specific relationship (twin flames, family bond) while others simply like the celestial imagery without deeper meaning attached.
Where it sits
This is a circular, radially symmetrical design, which suits the forearm, upper arm, shoulder, or thigh where the full sunburst can spread out evenly. It also works well centred on the sternum or spine if placement allows the rays to extend without being cropped. At small sizes, the fine rays around the edge will lose separation and the crescent's inner shading will disappear.
Making it yours
Ask an artist for any of these.